“…In recent years, researchers have established a variety of methods to detect SO 2 and FA. Among them, fluorescent probes are widely used in the study of various life phenomena in cells [ 20 , 21 , 22 ] and in vivo due to their advantages of low damage, high specificity, high sensitivity and real-time dynamic imaging [ 23 ]. In previous studies, benzopyranium has been proven to be an efficient structure to detect sulfur dioxide [ 24 , 25 ], and its recyclable and reversible detection with some oxidizing species may yet be realized [ 26 , 27 , 28 ].…”